The primary aims of the Neuromedical Core are to provide scientific leadership, participant evaluation, and data analysis and interpretation for studies focused on the clinical epidemiology, pathogenesis, and clinical management of neuroAIDS. To support these studies our Core Resource Objectives are to (1) perform structured assessments of HNRC study participants; (2) lead case conferences to triage participants and multi- disciplinary conferences to review progress in HNRC-based studies; (3) assign consensus neurocognitive diagnoses in collaboration with the Neurobehavioral Core; and (4) advise participants and staff in our areas of expertise. The Core's Scientific Objectives summarize our approach to better understanding and treatment the neurocognitive complications of HIV. We propose to (1) described incidence rates and immune and viral correlates of neurocognitive complications; (2) describe the plasma and CSF mediators; (3) standardize their diagnosis by validating diagnostic worksheets developed for the National NeuroAIDS Tissue Consortium; and (4) investigate their impact on medical adherence. Under funding by an HNRC-affiliated grant, we lead trials focused on their pathogenesis and treatment. The Core's ability to innovate and work collaboratively are among its greatest strengths. Our innovations span a spectrum from simplification and standardization of the diagnosis of HIV-associated neurocognitive syndromes to investigation of the roles of immune, anti- toxic, and anti-viral-based therapies in their treatment. In the pursuit of our broader scientific goals, the Core investigators have collaborated with distinguished virologists, national clinical trials organizations, and industry. The Core will be a resource to support new investigators, foster synergism across disciplines, and extend the scope of neuroAIDS research.